Virtual reality (VR) devices often rely on head mounted motion tracking devices for purposes of detecting head movement. The detected movement is then often interpreted as a change in head position within a virtual environment with the images of the virtual environment being changed to take into consideration the change in viewing position that would have resulted from the detected head movement if the user was in a real rather than a virtual environment.
Head mounted position tracking devices, such as those which may be included in a head mounted device and/or a cell phone which is part of a head mounted VR display system, tend to work well in stationary environments. For example is a user is sitting in a chair at home, the detected motion is likely to reflect head motion since the building in which the user is sitting is not likely to have significant movement.
One application for virtual reality headsets is as an entertainment device for passengers in a vehicle such as an aircraft or car. Head mounted VR devices because of their relatively compact size and ability to entertain a user for extended amounts of time are particularly well suited for use in such applications.
A problem with head mounted VR devices with motion tracking devices is that the devices will detect motion whether it is due to a user's head moving or the vehicle itself moving. When vehicle motion is detected and interpreted as movement of a user's head, the user who absent use of the VR headset has the sense of being stationary in a seat of a vehicle may be subject to a rather unsettling sense of motion in the virtual environment due to the motion that the motion tracking device in the VR headset may detect due to vehicle movement. This may cause the user to experience a sense of movement through a virtual environment despite being stationary in a seat of a car, plane or other vehicle.
In view of the above, it should be appreciated that there is a need for methods and/or apparatus which would allow a VR device to distinguish between motion that is detected due to head movement by a user of the device as opposed to movement due to motion of a vehicle in which a user is located.